This invention relates to adapters for electrical connectors, to permit an electrical connector to fit with a jack of a different size, with which it would not ordinarily fit. Thus, with such an adapter, electrical and electronic equipment is able to be connected to other electrical or electronic equipment with which it is not normally compatible because of differences in adapter and receptacle sizes.
More particularly, this invention relates to an adapter for electrically and mechanically coupling, in the field of cardiac pacemaking apparatus and the like, the terminal end of a sensing and/or pulse delivery lead of one size to a sensing and/or pulse delivery lead receptacle of another size.
Cardiac pacemaker and defibrillator systems are used to regulate the heartbeat. These devices may be surgically implanted in the body, and they may remain there for years. A typical implanted pulse generator, including the power supply and electronic circuits, operates by furnishing electrical pulses through a lead attached at the patient's heart, as required during disturbances in cardiac activity known as arrhythmia.
A pulse generator typically includes one or more receptacles, called connector cavities, into which the lead connectors may be inserted to form an electrical and mechanical connection. A lead connector typically comprises a pin for electrical contact, a sealing mechanism zone, and a hand grip zone. The lead connector pin is the electrically conductive element of the lead connector, and typically is mechanically and electrically connected to the connector contact of the connector cavity by a set screw. This retaining set screw may be loosened to permit withdrawal of the lead connector from the connector cavity, as for example when the pulse generator is to be replaced.
Conventional lead connectors and connector cavities customarily come in different sizes, which vary significantly among manufacturers. The current trend is to decrease the size of both lead connectors and connector cavities as materials and technologies allow, in order to reduce overall size of the implant. In view of the fact that the installed heart-stimulation lead generally lasts longer than the generator, it of course would be highly advantageous to reuse the implanted lead and thus avoid further surgery for explanation of the existing lead and implantation of a new lead, even when the lead connector is of a different size from the connector cavity of the replacement pulse generator.
This can be achieved by providing an adapter which is of the proper size to receive the implanted lead connector and plug into the replacement generator's connector cavity in a manner which establishes a reliable mechanical and electrical connection between the lead and the generator.
One such adapter is disclosed in U.S. Pat. No. 5,007,864 of Stutz. The device disclosed in this patent, however, accepts lead connectors of only a smaller size than the lead adapter, and is unable to be used with lead connectors which are larger than the connector cavity of the generator. Because the current trend is to reduce size as much as possible, it is likely that the replacement connector cavity will be smaller, not larger, so that in many commercial situations the Stutz invention will not be usable.
Another adapter is disclosed in U.S. Pat. No. 4,583,543 of Peers-Trevarton. The device of this patent also accepts lead connectors which are of only smaller size than the connector cavity of the generator. Thus it exhibits the same disadvantage as the previous design. Also, the device disclosed in this patent is relatively complex in design.
Other adapters are currently manufactured and function in part or primarily to extend a lead. This type of adapter comprises an adapter connector, similar to a lead connector, and a separate lead terminal receptacle similar to a connector cavity on a pulse generator, connected via a length of an insulated conductor. The resulting assembly is bulky in diameter and length. Such a receptacle typically uses a set screw mounted in a connector block which is covered by an elastomeric shell.
By this present invention, an adapter connector is capable of using standard lead design such as a pin having an elastomeric covering, so the difficulties of non-standard structure are avoided. Also in some embodiments a set screw connecting the adapter to the connector can be eliminated, for advantages of space saving and design simplification.